5 Answers
5

Ubuntu 11.04 is the latest version that uses Gnome 2 (Although this isn't exactly what you want, as you actually are talking about gnome-panel, which 11.04 uses Unity), but this version is no longer supported.

Ubuntu 10.10 is the latest version that uses gnome-panel by default, but this version is no longer supported.

Ubuntu 10.04.2 is the latest LTS release that uses gnome-panel, which is supported until April 2013 (for the Desktop) and April 2015 (for the server)